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Specific Flexibility In The
Hurdles

By Gunter Tidow, Germany

The statement that specific flexibility is a must for
high hurdlers is probably accepted by everyone (cf. Gambetta & Hill1981; Bush 1984; Pereversjov, et al. 1984 ). The question, however, as to
what degree of flexibility is needed precisely could---up to now---only be
answered subjectively by analyzing the movement behavior of world class
athletes. Doing so it is quite obvious that
within the split phase (Fig. 1) the knee flexors of the lead leg as well as the
hip flexors of the trail leg are highly stretched. On the other hand, within the
bar clearance (Fig. 2, F) and especially within the preparation for landing
phase (Fig. 2, G),considerable specific flexibility of the abductors of
the bent trail leg is indispensable.

Whereas corresponding range of motion
in the respective joints is a prerequisite for hurdle specialists, conditions
are sometimes quite different with decathletes and sports students. Apart from
this, even certain flaws of top hurdlers might be traced back to flexibility
deficiencies. This is why in my opinion a testing
apparatus was needed to assess hurdle-specific flexibility and to make available
set values that flexibility training can be directed
to.

Experts would remark here that the hurdle
sit table test (HSTT) has already been available for several years (cf. Grosser
1972). This is a definitely true. Our main objective, however, was to mirror the
above- mentioned phases of the hurdle stride as close as possible during
testing. Furthermore we felt that spreading and abducting abilities are
different demands needing different
tests. These considerations led to the
construction of the "hurdle-fleximeter ," by means of which the "Abduction Test"
(AT), as well as the "Split Test" (ST), can be performed (cf. Tidow 1983). The
hurdle-fleximeter (Fig. 3) consists of a wheeled upright with a T-shaped top.
The top is closely connected to the upper end of an aluminum pipe with a
yardstick on it. This measuring pipe slides vertically within a second pipe. If
you lift the top, the vertical distance from the T-level to the floor is
indicated at the upper rim of the guidance pipe.

The Abduction Test is performed as follows (Fig. 4). After making sure
that the subject remains in a vertical posture and having fixed his trail foot
to the T bar by means of a belt, he is asked to raise his bent and abducted
trail leg as high as possible and to hold the end position for at least 2 sec. A
test result of 97, for instance, indicates that the inner part of the ankle was
97cm above ground. Dividing 97 by the leg length (e.g., I00 cm) which was
measured before hand by means of the hurdle-fleximeter, too---the "AI," i.e.,
the "Abduction Index," can be computed. An index of .97 implies that the subject
has raised his ankle up to a level equal to 97% of his leg
length. To perform the Split Test the
hurdle-fleximeter has to be rearranged in the following way (Fig. 5):At first
the T -bar is fixed at 3ft. 6in., i.e., at high hurdle bar level. Then, a tape
measure, that is kept in a permanent stretched state by means of a counter
weight is connected with a little platform the subject is standing on. The
subject is asked to place his lead leg heel on the T-bar and to grip his lead
leg shank near the ankle with his counter arm (Fig. 6). For stability/safety
reasons the other hand should glide along a bar parallel to the extended lead
leg. Finally, the tester controls the advance of the wheeled fleximeter while
the subject increases the spreading distance between supporting and leading foot
by shifting body weight in the direction of the latter (Fig. 6).

When the spread maximum is attained,
the tester can read the corresponding result on the tape measure immediately.
The tape glides over one of the two rollers connected to the T-bar, thus in
plain view of the tester. The "Split Index"
(SI) is calculated by dividing the test result of, for instance, 190cm by
double-leg length (including the additional "lift" caused by the plantar flexion
of the trail foot). Thus an SI of .85 indicates that 85% of the
anthropometrically limited distances has been
attained. Comparison between body positions
during the tests with the corresponding phases of the hurdle strides how the
main requirements of the tests mentioned above have been fulfilled, at least to
a certain degree (Fig. 7 and Fig. 8).

In all, 100 male subjects took part in
the tests: the (national) best 51 junior decathletes, 44 sports students and 5
high hurdlers, among them the FRG (West German) champions (youth and
men). The main results are presented in Table
1.

As could be expected, the specific
flexibility of high hurdlers was far superior in both tests. This is why their
arithmetic means functioned as "set values" to assess stretching capacities of
the other groups. The (average) results of the best junior decathletes and of
the sports students did not differ
significantly. While the arithmetic
means--representing central tendencies--given in Table 1 may appear to be
acceptable, they tend to "conceal" individual val- ues. These individual results
may be either advantageous or limiting to the high hurdle technique. The
identification of individual flexibility deficiencies was, of course, the main
objective of the tests introduced here. A
comparatively low correlation of .62 between ST and AT results imply that
flexibility is not a general ability. This is why we suggest that Grosser's
Hurdle Sit Table Test (HSTf), which was also performed (but only by the sports
students) and which correlated far more closely with the Split Test (r=.75) than
with the Abduction Test (r=.41), should be applied primarily when there is lack
of time or for a more complex assessment. For differential diagnosis either ST
and AT should be performed
separately. Referring to technique the
following consequences can be derived fromlimited specific
flexibility:

1. Poor Split Test Results:

Due to the fact that the m. biceps femoris is a two-joint muscle, the
hurdle attack phase cannot be executed properly: An accentuated shift (forward
lean) of the upper body-with an erect spinal chord-would cause the lead leg
knee to bend. Consequently a flat trajectory is pre- vented-otherwise the foot
of the lead leg would collide with the bar.

If insufficient spreading abilities are caused by shortened hip
flexors, e.g. m. iliopsoas, the pushing leg cannot take over its "trailing
function" within the spread phase. Thus its knee is not-as it should be-well
be- hind the trunk, but far too early beneath the hip joint. Consequently the
deliberately delayed but (then) smooth and dynamic action of the trail leg is
hampered or even destroyed.

A further negative effect of limited spreading abilities is the
reduction or even prevention of producing a slight forward rotational impulse
around the lateral axis, needed for a quick touchdown after clearing the
hurdle.

2. Poor Abduction Test Results:

That limited abducting abilities (in an indirect way) affect the flight
curve negatively is known to everyone. This applies especially to the "hurdle
sit phase" (or bar clearance phase).

In addition a lack of abducting abilities prevents the hurdler from
compensating for the active downward movement of the lead leg after clearing
the hurdle by a reactive forward- upward action of the trail leg. Thus, the
needed forward lean of the upper body cannot be sustained.

Furthermore poor abduction capacities prevent the pelvis axis from
tilting (or slanting) towards the side of the lead leg. The tilt elongates the
length of the lead leg. Thus it can contact the ground earlier. Apart from
this the tilt provides a buffer-capacity for a smoother compensation to the
impact when landing.

Finally a higher-than-average abducting flexibility enables the athlete
to preserve a high level of the CG within the landing phase. Consequently the
contact time as well as the landing load of the supporting leg are reduced.
Thus the first stride of the inter-hurdle sprint can be performed staying tall
with a high knee lead.